The Researche Of The Stability Of Supercavity Flow And The Control Methods

Many countries had paid great attention to research supercavitation in recent years due to its bright future for its effect of drag reduction and speed acceleration. In order to keep the supercavition underwater vehicles moving steadily, the stability of theirs movements and motive forces which are closely related to the stability of the shape of supercavity must be researched. So it is very significant to study the stability of the shape of supercavity and control the shape initiatively. Because of the complexity of supercavity, the methods which included the self-programming and the commercial software were applied to simulate the shape property of unstability supercavity. The main works are as follows:A mathematical model of unstability ventilated supercavitation was obtained based on the principle of Logvinovich of the cavity sections expansion and mass conservation equation and using the mathematical model to simulate the shape stability of ventilated supercavitation under the disturbances of air-supply rate, cavitator, velocity, pressure and some combination thereof respectively, and then the stability of ventilated supercavitation was analyzed. Finally these parameters were compared and researched synthetically and a series of significant laws of stability of the supercavity shape were obtained.A numerical method has been brought forward to calculate the shape of supercavitation when underwater vehicles moving with changeable-depth at any trajectory based on the principle of Logvinovich of the cavity sections expansion, the trajectory equations and mass conservation equation. The influence of the shape of natural supercavitation and ventilated supercavitation had been researched when underwater vehicles moving with changeable-depth along skew lines or curved trajectory by this method, and the laws of the supercavity shape along with depth were obtained.A suction air control method has provided at the last chapter, namely decorating the air suction port or net on the underwater body. It can make the cavity close at the optional position of body by the suction effect, so the bedewed area of body can keep unchanging, and the lift force also keep unchanging when the other parameters are constant, then the underwater vehicles can achieve the stability of motive force. The effect of suction air control was researched in qualitativeanalysis by the multiphaseflow model of fluent software, and the schemes and influence parameters of air suction such as the pressure of suction air, air-supply rate, velocity, pressure of field, angle of pitch, angle of attack and bedewed area etc were simulated and analysed, the suction air control method was optimized at last.